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Help with Tangent TM1 Restoration

 
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bellwoods
Introductory Contributor


Joined: 23 May 2017
Posts: 4

PostPosted: Thu May 25, 2017 12:27 am    Post subject: Help with Tangent TM1 Restoration Reply with quote

Hello from Canada

I purchased a pair of Tangent TM1s back in 2002. They had the original KEF B200 woofer but tweets were blown. I replaced the tweets with Audacs TWO25AO and the B200's are still going strong.

Re-visiting them again now (2017) because I find they do not have the dynamic range I think needed for digital audio when driven with a truly ancient Sony 3200F power amp.

First step will be to upgrade to a higher power amp (to a Hafler DH500) and see if the crossover was loading the 3200F amp to the point of distortion.

But I have a couple of questions that I hope someone here might helpwith:

1) In the original were the tweets wired reverse polarity i.e. + of driver connected to - rail of crossover? Unfortunantely I didnt note this back in 2002. I expect this is a function of the crossover; the schematic can be found here: http://www.thunders.ca/tangent/tm1.php

2) Any opinions on whehter the Audacs TWO25AO is an appropriate tweet for these speakers? Any recomendations for something better suited?

3) Back in 2002 a fellow named William Smith at Wimslow Audio reccomended a SEAS H457 - any opinios on this tweet vs the Audacs? Is there a modern equivalent?

4) I'd like to model the crossover (which I rebuilt with all new components) - any reccomendations for software that would do this. (I am trianed as an engineer so should be able to learn)

Finally I have a fair bit of data (and experience) with these speakers so I welcome any inquires. The one comment I will make is that they seem to need a fair bit of equalisation (maybe the Audacs tweeter?).

Thanks in advance.[/img]
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bellwoods
Introductory Contributor


Joined: 23 May 2017
Posts: 4

PostPosted: Thu May 25, 2017 11:51 pm    Post subject: Reply with quote

When I did these I lined them with a mult-layer sound absorbing material that is normally used inside marine engine compartments.
The outer layer is a convoluted (spiked) high density foam about 1.5 inches peak to peak which is then backed up by other layers of high density foam materials.
I cant find the exact material I used but here are some similar:

http://www.defender.com/product.jsp?path=-1&id=3018062

https://www.aixfoam.com/technical-acoustics/sound-absorbers-building-loudspeakers
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Gary
Senior Contributor 200+


Joined: 07 Nov 2004
Posts: 274
Location: Toronto, Canada

PostPosted: Sat Jul 15, 2017 10:58 am    Post subject: Reply with quote

I'm not an expert but I never noticed if the tweeters were reverse polarity wired. I would have to say "No" because I believe that was an old trick to get more high end from cheap speakers. And these were not cheap speakers. Smile

As for Audex and Seas - you're in the right area but I don't have any experience with the models that you mentioned.

Good luck!
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Sometimes I lie awake at night, and I ask, "Where have I gone wrong?" Then a voice says to me, "This is going to take more than one night."
-- Charles M. Schulz (as Charlie Brown)
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bellwoods
Introductory Contributor


Joined: 23 May 2017
Posts: 4

PostPosted: Sat Jul 15, 2017 3:59 pm    Post subject: Reply with quote

Some updates:

A schematic of the crossover is fund here: http://www.thunders.ca/tangent/tm1.php

Having dismantled the entire speaker and traced out the crosover circuit I can say that the schmatic is correct except that I measured the inductor shown in the schematic as 1.088 mH at 2 mH . Also in the originals the inductors were ferrite core whereas I used air core (larger physical size less prone to saturation).

I found a circuit simulation software for modelling crossovers that is relatively low cost (even less for students) called Circuitlogix
https://www.circuitlogix.com/student_version.php

I obtained several other software tools:
True RTA relatime spectrum analyzer which I have used in conjunction with a Umik 1 calibrated microphone and WinSpeakrz (which i have not yet used) that analyzes cabinet designs and has a couple of crossover circuits. Both are here
https://trueaudio.com/rta_abt1.htm

The conclusion of all this is that the "liiving room" response of these tangent speakers shows a real +10db peak between 30 and 60Hz and then a -10db drop between 130 and 250Hz. I compared this to a couple of other speaker system and found that they exhibited similar peak 30-60hz but not the drop off 130 to 250Hz

To study the effect of correcting these I deployed a trail version of Dirac equaliiztion software on the PC I use a source (Foobar player Musical Fidelity DAC) and found that the reusulting Dirac corrected repsonse solved all the issues of concern to me.
Here is Dirac https://www.dirac.com/

Dirac is constly but there are alternatives:
1) Math Audio makes a much lower cost alternative to Dirac that works with Foobar player
http://mathaudio.com/room-eq.htm
2) For a software implementation of a traditional 1/3 octave equalizer see:
Graphic Studio Equalizer
http://www.pas-products.com/eqstudio.html
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